Pennsylvania updating cancer data report after error discovered

“The Pennsylvania Department of Health is updating a comprehensive report on cancer rates in Bucks and Montgomery counties after reporters from this news organization found a significant error in the analysis.

Over the past two years, the health department has studied cancer rates in areas near Horsham, Warminster and Warrington in an effort to address ongoing concerns over perfluorinated chemicals, or PFAS, contamination in area groundwater. The unregulated chemicals were found in nationally high amounts in the three towns’ drinking water in 2014 and 2016, prompting numerous public and private water well closures since.

An initial 2016 report conducted with the U.S. Centers for Disease Control and Prevention’s Agency for Toxic Substances and Disease Registry included an analysis of nearly 30 years of data for seven types of cancer that have been linked to PFAS and other contaminants in the primary ZIP codes for Warminster, Warrington and Horsham, but the results were ‘inconclusive’ and didn’t meet the official definition of a ‘cancer cluster.’

A separate analysis by this news organization pointed out that ZIP codes may not have been the most accurate way to analyze the affected areas, and also found rates of some cancers — particularly bladder cancer — were higher in areas where the contamination may have been greater…

A second addendum released last week was supposed to be the health department’s most refined analysis to date, as it zeroed in on residents of the water districts impacted by the chemical contamination. The department looked at data for nine types of cancer, in areas served by the Horsham Water and Sewer Authority, Warminster Municipal Authority, and Warrington Township Water and Sewer Department, and where Warrington’s department and North Wales Water Authority work jointly.

However, reporters with this news organization cross-checked the report’s data against their own spreadsheets developed during their initial discovery that cancer rates in some of the affected areas appeared to greatly exceed county and state averages. Reporters pointed out to the state that it appeared cancer rate information for Warminster and a section of Warrington appeared to be switched. In an email Thursday, health department spokesperson Nate Wardle confirmed the state’s researchers had incorrectly switched the data.

‘There were some columns in the cancer addendum in which the labels were reversed,’ Wardle wrote in an email. ‘The results will also need to be amended, as well as any findings that came out of that.’

Wardle said early Friday afternoon the department was updating the report and expected it to be published by the end of the day. As of late Friday afternoon, it was unchanged on the department’s website.

Until the update is made, the extent of the errors and changes is not known. It appears the results will be significantly different, with the number of certain types of cancers expected to jump by at least 100 cases in Warminster, over what was incorrectly analyzed before.”